Wire bonding device, method for manufacturing semiconductor device, and semiconductor device

Abstract

The present invention provides a wire bonding device, a method for manufacturing a semiconductor device, and a semiconductor device, which can reduce the arc height. The wire bonding device includes a porcelain nozzle, a moving mechanism for moving the porcelain nozzle, and a control unit for controlling the driving of the moving mechanism, wherein the control unit at least performs: a first process (track a), in which the porcelain nozzle is lowered to the first bonding point to the crimping height after the FAB is formed, thereby forming a crimping ball and a cylindrical portion at the first bonding point; a second process (track b), in which the porcelain nozzle is horizontally moved at the crimping height after the first process is performed, thereby cutting off the cylindrical portion with the porcelain nozzle; and a third process (tracks c to k), in which the porcelain nozzle is moved in the forward direction after the second process is performed, and a flattening action is repeatedly performed more than once in the middle of the movement, wherein the flattening action temporarily lowers the porcelain nozzle in order to flatten the wire portion overlapping the crimping ball with the porcelain nozzle.

Description

Technical Field

[0001] This specification discloses a wire bonding device for connecting a first bonding point and a second bonding point provided on a mounted body with a wire, a method for manufacturing a semiconductor device, and a semiconductor device. Background Art

[0002] In recent years, with the high functionality of mobile information terminals, digital audio-video (AV) devices, integrated circuit (IC) cards, etc., the semiconductor chips carried are required to be miniaturized, thinned, and highly integrated. In particular, in stacked memory devices, the memory capacity is sought by the number of chips that can be stacked. Therefore, it becomes important to stack more semiconductor chips within the determined package height. In order to meet this requirement, it is necessary to suppress the height of the wire loop formed by wire bonding. Therefore, a large number of low arc technologies that suppress the arc height have been proposed before.

[0003] Here, one end of the wire connecting the first junction and the second junction has a flat disc-shaped crimping ball and a cylindrical portion overlapping the crimping ball. Most existing low arc technologies are looping with the cylindrical portion directly remaining on the crimping ball, so it is difficult to sufficiently reduce the arc height.

[0004] Here, Patent Document 1 discloses a wire bonding method that can form a low arc. Specifically, Patent Document 1 performs the following steps: In the first step, after the free air ball at the front end of the porcelain nozzle is crimped to the first joint point to form a crimped ball of the required crimping thickness, the porcelain nozzle is raised and then moved toward the second joint point, thereby pressing the side of the upper part (cylindrical part) of the crimped ball to form the top of the crimped ball; and in the second step, after the first step, the porcelain nozzle is raised and then moved toward the second joint point and lowered to press the wire from obliquely above. According to the technology of Patent Document 1, a part of the upper part (cylindrical part) of the crimped ball is collapsed by the porcelain nozzle, so the arc height can be reduced to a certain extent.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 4625858 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, in the technology of Patent Document 1, only a part of the cylindrical portion is collapsed, so it is difficult to sufficiently reduce the arc height. Therefore, this specification discloses a wire bonding device, a method for manufacturing a semiconductor device, and a semiconductor device that can further reduce the arc height.

[0010] Technical means of solving problems

[0011] The wire bonding device disclosed in the present specification connects a first bonding point and a second bonding point provided on a mounted body with a wire, and includes: a porcelain nozzle for holding the wire; a moving mechanism for moving the porcelain nozzle relative to the mounted body; and a control unit for controlling the driving of the moving mechanism, and the control unit at least performs the following processing: a first processing, after forming an airless ball at the front end of the wire, the porcelain nozzle is lowered to a predetermined crimping height toward the first bonding point, thereby forming a crimping ball and a cylindrical portion located on the crimping ball at the first bonding point; a second processing, after performing the first processing, the porcelain nozzle is horizontally moved at the crimping height, thereby shaving off the cylindrical portion with the porcelain nozzle; and a third processing, after performing the second processing, the porcelain nozzle is moved in a forward direction as a direction approaching the second bonding point at a moving height higher than the crimping height, and a flattening action is repeated more than once in the middle of the movement, wherein the porcelain nozzle is temporarily lowered in order to flatten the wire portion overlapping the crimping ball with the porcelain nozzle.

[0012] In the case of the above-described structure, the cylindrical portion is cut by the porcelain nozzle, and the portion of the wire overlapping the crimping ball is flattened by the porcelain nozzle, so that the arc height can be further reduced.

[0013] In the above case, the control unit may horizontally move the nozzle in a backward direction, which is a direction away from the second joining point, in the second process.

[0014] Furthermore, the control unit may cause the porcelain nozzle to horizontally move at least by an amount greater than the diameter of the cylindrical portion in the second process.

[0015] With the above configuration, the cylindrical portion can be cut almost reliably.

[0016] Furthermore, in the third process, the control unit may change the horizontal position of the porcelain nozzle and perform the squeezing action twice or more in order to completely press the wire portion overlapping the crimping ball with the porcelain nozzle.

[0017] By adopting the above structure, the thickness of the first joint portion and even the arc height can be further reduced.

[0018] Furthermore, the control unit may generate a moving order of the porcelain nozzle based on the shape information of the porcelain nozzle, the target shape information of the crimping ball, and the information of the wire.

[0019] By adopting the above-mentioned structure, the man-hours of the operator can be reduced.

[0020] As another method for manufacturing a semiconductor device of the present invention, a semiconductor device is manufactured by connecting a first joint point and a second joint point with a wire using a porcelain nozzle, and the method includes the following steps: a first step, after forming an air-free ball at the front end of the wire inserted into the porcelain nozzle, lowering the porcelain nozzle toward the first joint point to a specified crimping height, thereby forming a crimping ball and a cylindrical portion located on the crimping ball at the first joint point; a second step, after executing the first step, moving the porcelain nozzle horizontally at the crimping height, thereby shaving off the cylindrical portion with the porcelain nozzle; and a third step, after executing the second step, moving the porcelain nozzle in a forward direction that is a direction approaching the second joint point at a moving height higher than the crimping height, and repeating a flattening action more than once in the middle of the movement, wherein the flattening action raises and lowers the porcelain nozzle in order to flatten the wire portion overlapping the crimping ball with the porcelain nozzle.

[0021] In the case of the above-described structure, the cylindrical portion is cut off by the porcelain nozzle, and the portion of the wire overlapping the crimping ball is flattened by the porcelain nozzle, so that the arc height can be further reduced.

[0022] Another semiconductor device of the present invention comprises a first joining point on a semiconductor chip and a second joining point on a lead frame on which the semiconductor chip is mounted, connected via a wire arc, the wire arc having a first joining portion formed at the first joining point, and a second joining portion formed at the second joining point and connected to the first joining portion via the wire, the first joining portion being in a shape in which a portion of the wire that is squeezed toward the crimping ball is placed at a predetermined interval on a flat circular plate-shaped crimping ball, and the wire extends approximately horizontally from an end of the first joining portion.

[0023] Since a part of the collapsed wire is directly placed on the press-bonded ball, the thickness of the first bonding portion and even the arc height are reduced, thereby achieving a further reduction in the thickness of the semiconductor device.

[0024] In the above case, the arc height, which is the distance from the upper surface of the semiconductor chip to the highest point of the wire arc, may be smaller than the total value of the thickness of the press-bonded ball and the diameter of the wire, or may be equal to the total value.

[0025] With the above structure, the thickness of the first bonding portion and even the arc height can be reduced, thereby achieving a further reduction in the thickness of the semiconductor device.

[0026] Effects of the Invention

[0027] According to the wire bonding device, semiconductor device manufacturing method and semiconductor device disclosed in this specification, the cylindrical portion is cut off by the porcelain nozzle, and the wire portion overlapping the crimping ball is flattened by the porcelain nozzle, so the arc height can be further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A diagram showing the structure of a wire bonding device.

[0029] Figure 2 A diagram showing the shape of the front end of a porcelain nozzle.

[0030] Figure 3 A diagram showing an example of a line arc shape.

[0031] Figure 4 A diagram showing the movement trajectory of the porcelain nozzle.

[0032] Figure 5 It is a figure which shows the state when the first bonding part is formed.

[0033] Figure 6 It is a figure which shows the state when the first bonding part is formed.

[0034] Figure 7 A table showing the experimental results.

[0035] Figure 8 This is a photograph showing an example of the first joining portion formed by the technique disclosed in this specification.

[0036] Fig. 9 It is a figure which shows the state of formation of the conventional first joint part.

[0037] Fig.10 It is a figure which shows the state of formation of the conventional first joint part.

[0038] Explanation of symbols

[0039] 10: Wire bonding device

[0040] 12: Porcelain mouth

[0041] 14: Joint Arm

[0042] 16 joint heads

[0043] 18: XY stage

[0044] 20: Platform

[0045] 21: Chuck

[0046] 22: Discharge electrode

[0047] 24: Control Department

[0048] 40: Hole

[0049] 42: Chamfered surface

[0050] 44: Facing side

[0051] 50: Wire

[0052] 54: First joint

[0053] 58: Second joint

[0054] 60: Press the ball

[0055] 62: Cylindrical part

[0056] 110: Semiconductor chips

[0057] 112: Padding

[0058] 120: Lead frame

[0059] 122: Lead DETAILED DESCRIPTION

[0060] Hereinafter, the structure of the wire bonding apparatus 10 will be described with reference to the drawings. Figure 1 1 is a diagram showing the structure of a wire bonding device 10. The wire bonding device 10 is a device for connecting a first bonding point P1 and a second bonding point P2 with a wire 50. Generally speaking, the first bonding point P1 is set on a pad 112 of a semiconductor chip 110, and the second bonding point P2 is set on a lead 122 of a lead frame 120 on which the semiconductor chip 110 is mounted.

[0061] The wire bonding device 10 includes a bonding head 16 and a stage 20 on which a lead frame 120 (hereinafter referred to as a "mounted body" when the two are collectively referred to) on which a semiconductor chip 110 is mounted is placed. The bonding head 16 also includes a bonding arm 14 that functions as an ultrasonic welding head and a porcelain nozzle 12 mounted on the front end of the bonding arm 14. The bonding arm 14 is an arm that protrudes horizontally from the bonding head 16, and an ultrasonic vibrator is incorporated therein. By applying a voltage to the ultrasonic vibrator using an ultrasonic oscillator (not shown) provided in the wire bonding device 10, ultrasonic vibration can be imparted to the porcelain nozzle 12 located at the front end of the bonding arm 14.

[0062] The porcelain nozzle 12 is mounted on the front end of the joint arm 14 in a manner that it faces the platform 20 up and down. A through hole (hereinafter referred to as "hole 40") that penetrates in the axial direction is formed in the porcelain nozzle 12. Figure 1(not shown), a conductor 50 such as a gold wire is inserted into the hole 40. The porcelain nozzle 12 is appropriately replaced according to the type of the conductor 50 used or the shape of the required crimping ball 60.

[0063] A discharge electrode 22 is disposed near the porcelain nozzle 12. The discharge electrode 22 is provided to form a free air ball (hereinafter referred to as "FAB52") formed by melting the wire 50 at the front end of the wire 50. When a high voltage is applied between the discharge electrode 22 and the front end of the wire to generate a discharge, the front end of the wire 50 is melted by the discharge energy. Then, the FAB52 is formed at the front end of the wire 50 by the melting.

[0064] A chuck 21 is disposed above the porcelain nozzle 12. The chuck 21 has a pair of gripping members disposed on both sides of the wire 50, and the wire 50 is gripped or released by moving the gripping members closer or farther away.

[0065] The bonding arm 14 is mounted on the bonding head 16 via a lifting mechanism not shown. In addition, the bonding head 16 is set on the XY stage 18 and can move in the horizontal direction. Moreover, along with the horizontal movement of the bonding head 16 and the vertical movement of the bonding arm 14, the porcelain nozzle 12 can move relative to the mounted body in the horizontal direction and the vertical direction. That is, the lifting mechanism and the XY stage 18 function as a moving mechanism that moves the porcelain nozzle 12 relative to the mounted body. Furthermore, in this example, the porcelain nozzle 12 is moved, but it can also be set as a structure that moves the platform 20 instead of the porcelain nozzle 12.

[0066] The stage 20 is used to place a mounted object, that is, a lead frame 120 mounted with a semiconductor chip 110. A heater (not shown) for heating the lead frame 120 is built into the stage 20. The lead frame 120 is heated by the heater when wire bonding is performed.

[0067] The control unit 24 controls the driving of each part of the wire bonding device 10. The control unit 24 includes, for example, a memory for storing various data and a central processing unit (CPU) for performing various calculations. The data stored in the memory of the control unit 24 include a control program for executing the bonding process, data required for generating a movement sequence of the nozzle 12 described later, and the like.

[0068] Specifically, the control unit 24 controls the position of the porcelain nozzle 12 relative to the mounted body by driving and controlling the XY stage 18 and the lifting mechanism. In addition, the control unit 24 also controls the opening and closing of the chuck 21, the application of the discharge voltage, and the driving control of the heater of the platform 20 according to the progress of the bonding process. In addition, the control unit 24 also functions as a generating unit for generating the movement sequence of the porcelain nozzle 12 (the driving sequence of the XY stage 18 and the lifting mechanism). In order to generate the movement sequence, the memory of the control unit 24 stores information related to the shape of the porcelain nozzle 12, information related to the target shape of the crimping ball 60 described later, etc., which will be described later.

[0069] Figure 2 FIG. 1 is a diagram showing an example of the front end of the porcelain nozzle 12. The porcelain nozzle 12 is formed with a hole 40 as a through hole extending in the axial direction thereof. A wire 50 is inserted into the hole 40. Therefore, the diameter of the hole 40 (hole diameter H) is larger than the diameter of the wire 50 (wire diameter ) The lower end of the hole 40 expands in a conical shape. The conical surface expanding in a conical shape is called a chamfered surface 42. In addition, the maximum diameter (that is, the diameter at the lowermost end) in the conical space is called a chamfer diameter CD.

[0070] The lower end surface of the porcelain nozzle 12 becomes the facing surface 44 for pressing the FAB 52. The facing surface 44 can be a flat horizontal surface, or a sloped surface that moves upward as it approaches the outside. Hereinafter, the width of the facing surface 44, that is, the distance from the inner peripheral edge of the lower end of the hole 40 to the outer peripheral edge of the lower end of the porcelain nozzle 12, is referred to as the "facing width W". When the outer diameter of the porcelain nozzle 12 is set to T, the facing width W is W = (T-CD) / 2.

[0071] Figure 3 1 is a conceptual diagram of a wire arc formed by the wire bonding apparatus 10. A plurality of pads 112 are provided on the semiconductor chip 110, and a plurality of leads 122 are provided on the lead frame 120. The wire bonding apparatus 10 connects a first bonding point P1 located on the pad 112 and a second bonding point P2 located on the lead 122 with a wire 50.

[0072] At the first bonding point P1, a first bonding portion 54 is formed by pressing one end of the wire 50 against the pad 112, and the wire 50 extending from the first bonding portion 54 extends to the second bonding point P2. At the second bonding point P2, a second bonding portion 58 is formed by pressing the other end of the wire 50 against the lead 122. Here, the second bonding portion 58 is generally a stitch bond in which the wire 50 is pressed against the lead 122 and collapsed.

[0073] In order to make the semiconductor device thinner, it is necessary to reduce the height of the arc, especially the vertical distance from the upper surface of the pad 112 to the uppermost point of the arc, that is, the arc height HL. In this specification, in order to reduce the arc height HL, the first joint 54 is formed by a special step. In this regard, a comparison with the prior art is described. Furthermore, in the following description, the direction approaching the second joint point P2 from the first joint point P1 is referred to as the "forward direction", and the direction away from the second joint point P2 is referred to as the "retracting direction".

[0074] First, the formation of the conventional first joining portion 54 will be briefly described. Fig. 9 1 is a conceptual diagram showing a conventional process of forming the first bonding portion 54. When forming the first bonding portion 54, first, a press-bonded ball 60 is formed at a first bonding point P1 located on the pad 112 of the semiconductor chip 110. Specifically, first, Fig. 9 As shown in (a), FAB52 is formed at the front end of the wire 50. Fig. 9 As shown in (b), the porcelain nozzle 12 is lowered toward the first joining point P1, and the FAB52 is pressed against the first joining point P1 by the facing surface 44 of the porcelain nozzle 12. Furthermore, during the pressing, vibration may be imparted to the porcelain nozzle 12 via the joining arm 14. Accompanying the pressing, the FAB52 is deformed into a flat shape, and a flat disc-shaped crimping ball 60 is formed on the gasket 112. In addition, a portion of the material constituting the FAB52 is filled in the hole 40 of the porcelain nozzle 12. The material filled in the hole 40 constitutes a cylindrical portion 62 having a smaller diameter than the crimping ball 60 and a larger diameter than the wire 50. Moreover, by the pressing, a first joining portion 54 having a cylindrical portion 62 is formed on the flat disc-shaped crimping ball 60 at the first joining point P1.

[0075] If the first joint portion 54 is formed, the control unit 24 moves the nozzle 12 to bend the wire 50 toward the second joint point P2. Fig. 9 As shown by the arrow in (b), the porcelain nozzle 12 is moved upward, backward, and upward, and the wire 50 is bent, and then the porcelain nozzle 12 is moved to the second joint point P2. Then, at the second joint point P2, the porcelain nozzle 12 is pressed against the lead 122 to form a second joint portion 58 (stitch joint) that collapses the wire 50. If the second joint portion 58 is formed, the control unit 24 moves the porcelain nozzle 12 upward, and then further moves the porcelain nozzle 12 upward while locking the chuck 21, so as to break the wire 50.

[0076] The periphery of the first joint portion 54 formed by the above sequence is as follows Fig. 9As shown in (c), the wire 50 is shaped as follows: after extending upward from the upper end of the first joint 54, it draws a gentle arc and extends obliquely downward. In this case, the arc height HL is the sum of the thickness of the crimping ball 60, the thickness of the cylindrical portion 62, and the height of the wire 50 extending from the cylindrical portion 62 in a substantially U-shaped shape. The arc height HL is relatively high and is equal to the wire diameter. The large arc height HL hinders the thinning of semiconductor devices, and even the miniaturization, thinning, and high integration of semiconductor devices.

[0077] Therefore, a technique for reducing the arc height HL has been studied. For example, the following techniques are currently proposed: Fig.10 As shown in FIG. 1 , after the crimping ball 60 is formed at the first joint point P1, the wire 50 is folded back on the crimping ball 60, and the folded back wire is pressed by the porcelain nozzle 12. Specifically, if the crimping ball 60 and the cylindrical portion 62 are formed, the control unit 24 controls the porcelain nozzle 12 as follows: Fig.10 After moving upward, backward, downward, and upward as shown by the arrow in (a), it moves in the forward direction again, and moves downward again at the above location. Thus, the wire 50 is folded back on the crimping ball 60. Then, in the same manner as the usual bending action, the porcelain nozzle 12 is moved upward, backward, and upward, and after bending, moves to the second joint point P2.

[0078] According to the above technology, the wire 50 does not rise vertically from the first joint portion 54, but extends in a substantially horizontal direction, so that Fig. 9 Compared with the technology shown in the figure, the arc height HL can be reduced. However, in the technology, the cylindrical portion 62 is tilted laterally, and the wire 50 is placed on the tilted cylindrical portion 62. Although the cylindrical portion 62 and the wire 50 are pressed by the porcelain nozzle 12, it is difficult to fully reduce their height by simply pressing. In particular, the cylindrical portion 62 becomes harder than other parts due to work hardening caused by forming the crimping ball 60. It is difficult to fully reduce the thickness of the cylindrical portion 62 when it is pressed only by the porcelain nozzle 12. As a result, Fig.10 The arc height HL obtained by the technology is mostly a function of the thickness Bt of the press-fit ball 60 and the wire diameter. For example, when the wire diameter is 18 μm and the thickness Bt of the press-bonded ball 60 is 7 μm, Fig.10 The arc height HL obtained by the technology is about 25μm.

[0079] The wire bonding device 10 disclosed in this specification further reduces the arc height HL. Specifically, in this device, after forming the crimping ball 60 and the cylindrical portion 62, the porcelain nozzle 12 is directly moved horizontally without moving upward, thereby using the porcelain nozzle 12 to cut the cylindrical portion 62, thereby achieving a low arc. Figures 4 to 6This is explained. Figure 4 : is a diagram showing the movement trajectory of the porcelain nozzle 12 when the first joint portion 54 is formed. Figure 5 , Figure 6 1 is a diagram showing the movement of the porcelain nozzle 12 and the wire 50 when the first joint portion 54 is formed. Figure 5 , Figure 6 The letters a to l in the figures are Figure 4 The tracks a to m shown correspond to each other.

[0080] When forming the first joint 54, the control unit 24 first releases the chuck 21, and drives and controls the XY stage 18 and the lifting mechanism in the above state to move the porcelain nozzle 12 to the top of the first joint point P1. Then, the control unit 24 applies a high voltage between the discharge electrode 22 and the front end of the wire 50 to generate discharge, and forms FAB52 at the front end of the wire 50.

[0081] When FAB52 is formed, the control unit 24 lowers the nozzle 12 to the first joint point P1. At this time, the distance from the upper surface of the gasket 112 to the lower end of the nozzle 12 (hereinafter referred to as "pressing height H1") is determined based on the target value of the thickness Bt of the press-bonded ball 60.

[0082] Figure 4 The trajectory a represents the trajectory when the porcelain nozzle 12 is lowered to the crimping height H1. Figure 5 The left end of the upper section of shows the condition of the porcelain nozzle 12 and the wire 50 of the track a. In addition, during the descending, ultrasonic vibration can also be imparted to the porcelain nozzle 12 via the bonding arm 14.

[0083] As the nozzle 12 descends, the FAB 52 is pressed and flattened by the facing surface 44 of the nozzle 12. In addition, part of the material constituting the FAB 52 is filled in the hole 40 of the nozzle 12. As a result, Figure 5 As shown in the upper left end of FIG. 1 , a flat disk-shaped press-bonded ball 60 and a cylindrical portion 62 placed on the press-bonded ball 60 are formed at the first joining point P1. The step and process of forming the press-bonded ball 60 and the cylindrical portion 62 are the first step and the first process.

[0084] If the crimping ball 60 is formed, the control unit 24 then moves the porcelain nozzle 12 horizontally at the crimping height H1, and uses the porcelain nozzle 12 to cut off the cylindrical portion 62. Figure 4 As shown in the trajectory b, the porcelain nozzle 12 is not raised. In other words, the cylindrical portion 62 is kept in the hole 40 of the porcelain nozzle 12, and the porcelain nozzle 12 is moved horizontally in the backward direction. Figure 5The figure in the center of the upper section shows the situation at this time. In the above situation, it is natural that the inner circumference of the hole 40 interferes with the cylindrical portion 62. The porcelain nozzle 12 interferes with the cylindrical portion 62 while moving horizontally, so that the cylindrical portion 62 is cut by the porcelain nozzle 12. The material of the cut cylindrical portion 62 is as follows Figure 5 As shown by the darkened shadow in the center of the upper section, a part of it gradually moves laterally, and a part of it gradually moves inside the hole 40. In short, the porcelain nozzle 12 moves horizontally without rising after forming the crimping ball 60, thereby cutting off the cylindrical part 62. The step and process of cutting off the cylindrical part 62 are equivalent to the second step and the second process.

[0085] Here, the distance of horizontal movement of the porcelain nozzle 12 (movement distance of trajectory b) is not particularly limited. However, the second step (trajectory b) is for the purpose of cutting the cylindrical portion 62, so in the second step, it is more ideal to move the porcelain nozzle 12 horizontally by more than the diameter of the cylindrical portion 62. In addition, regarding the direction of horizontal movement of the porcelain nozzle 12, as long as the cylindrical portion 62 is cut off, it can be in the backward direction or the forward direction. In addition, as long as the cylindrical portion 62 is cut off, the porcelain nozzle 12 can also move forward and backward more than once in the backward direction and the forward direction. In addition, in order to smoothly perform the cutting action, ultrasonic vibration can also be given to the porcelain nozzle 12 during the movement of trajectory b.

[0086] If the second step is completed, the control unit 24 then executes the following third step (third processing), that is, the porcelain nozzle 12 moves in the forward direction at a moving height H2 higher than the crimping height H1, and repeats the flattening action of raising and lowering the porcelain nozzle 12 more than once during the movement. Trajectory c to trajectory k represent the movement trajectory of the porcelain nozzle 12 in the third step. In addition, Figure 5 From the upper right end to Figure 6 The center of the lower section shows the status of the third step.

[0087] Specifically, if the cylindrical portion 62 is cut off, the control unit 24 moves the porcelain nozzle 12 upward (track c) and then moves it forward by a predetermined distance (track d). Figure 5 As shown in the upper right end and the lower left end of the figure, the wire 50 is folded back to the forward side and placed on the crimping ball 60. If the above state is reached, the control unit 24 moves the porcelain nozzle 12 downward (track e), as shown in FIG. Figure 5 As shown in the center of the lower section, the wire 50 on the crimping ball 60 is flattened by the facing surface 44 of the porcelain nozzle 12. As a result, part of the material of the flattened wire 50 is evacuated to the outside of the porcelain nozzle 12, and the other part is evacuated to the inside of the hole 40 of the porcelain nozzle 12. On the other hand, the thickness of the first joint portion 54 directly below the facing surface 44 is greatly reduced.

[0088] Here, the folded wire portion includes the material constituting the cylindrical portion 62 (darkened area). The cylindrical portion 62 is harder than other portions as described above. Therefore, the original cylindrical portion 62 is difficult to deform and reduce in thickness when it is only flattened by the porcelain nozzle 12. However, at the time point, the cylindrical portion 62 is cut and destroyed by the porcelain nozzle 12. Therefore, it is easy to deform and reduce in thickness by being flattened by the porcelain nozzle 12.

[0089] When the conductive wire 50 is compressed by the facing surface 44, ultrasonic vibration may be applied to the nozzle 12. In short, the operation of temporarily lowering the nozzle 12 in this manner (operation of trajectory e, trajectory h, and trajectory k) is hereinafter referred to as "compression operation".

[0090] The control unit 24 repeatedly performs the squeezing operation a plurality of times while changing the horizontal position until the wire 50 reaches the end of the advancing side of the crimping ball 60. In this example, the control unit 24 performs the squeezing operation three times. Figure 4 The trajectory of e, Figure 5 The lower center of the is the first squeezing action. Figure 4 The trajectory h, Figure 6 The middle of the upper part shows the second squeezing action. Figure 4 The trajectory k, Figure 6 The lower center of the figure indicates the third squeezing action. Figure 5 , Figure 6 As shown, by repeating the squeezing operation until the wire 50 reaches the end of the crimping ball 60 on the forward side, the wire 50 can be extended from the end of the crimping ball 60 on the forward side while keeping the thickness of the first joint portion 54 thin.

[0091] Here, the number of times the squeezing operation is performed and the horizontal intervals (distances of the tracks d, g, and j) are preferably set so that the entire conductor 50 placed on the crimping ball 60 is squeezing by the facing surface 44 on the rearward side of the hole 40 .

[0092] In addition, the moving height H2 is set based on the range within which the wire 50 can be folded back. If the moving height H2 is too small, the wire 50 is difficult to fall down and cannot be folded back. On the other hand, if the moving height H2 is larger than necessary, it will take unnecessary time. Here, it is preferable to find out the appropriate value of the moving height H2 according to the wire diameter or material of the wire 50 used by experiments in advance and store it in the control unit 24 in advance.

[0093] The height of the porcelain nozzle 12 when flattened, i.e., the flattening height H3, is preferably substantially the same as the crimping height H1. However, in reality, it is difficult to set H3=H1 due to the resistance of the wire 50 flattened by the porcelain nozzle 12, and in reality, H3

[0094] If the third step is completed, the control unit 24 performs an arc bending action to extend the wire 50 toward the second joint point P2. Specifically, if the final flattening action is completed, the control unit 24 moves the porcelain nozzle 12 in the forward direction at the flattening height H3 ( Figure 4 After the trajectory l), move upward ( Figure 4 Then, the control unit 24 moves the porcelain nozzle 12 obliquely downward toward the second joining point P2.

[0095] When the porcelain nozzle 12 reaches the second joint point P2, the control unit 24 lowers the porcelain nozzle 12 toward the second joint point P2, and presses the wire 50 against the lead 122. Here, ultrasonic vibration is applied to the porcelain nozzle 12 as needed. By the pressing, a stitch joint as the second joint portion 58 is formed at the second joint point P2 (lead 122). When the above state is reached, the control unit 24 slightly raises the porcelain nozzle 12, and then locks the chuck 21. Then, the porcelain nozzle 12 is moved laterally while the chuck 21 is locked, and the wire 50 is pulled off.

[0096] As shown in the above description, in the wire bonding device 10 disclosed in this specification, after forming the crimping ball 60 and the cylindrical portion 62, the porcelain nozzle 12 is horizontally moved at the crimping height H1, thereby cutting off the cylindrical portion 62 located on the crimping ball 60. Furthermore, after cutting off the cylindrical portion 62, the porcelain nozzle 12 flattens the wire 50 folded on the crimping ball 60. As a result, the thickness of the first bonding portion 54 can be greatly reduced, and even the arc height HL of the wire arc can be greatly reduced.

[0097] Figure 7 The table shows the experimental results of wire bonding performed using the wire bonding apparatus 10 disclosed in this specification. The gold wire conductor was formed into 30 arcs, and the thickness Bt, arc height HL and pull strength of the crimped ball 60 of each arc were measured.

[0098] like Figure 7 ​As shown, according to the technology disclosed in this specification, the thickness Bt of the press-bonded ball 60 is 6.6 μm to 7.2 μm (average 6.9 μm), and the arc height HL is 19.8 μm to 21.5 μm (average 20.5 μm). Fig.10 As described above, the arc height HL of the prior art shown is the sum of the thickness of the crimping ball 60 and the wire diameter. In other words, according to the technology disclosed in this specification, Fig.10 Compared with the prior art shown in FIG. 1 , the arc height HL can also be reduced by about 20%. In addition, the tensile strength of the wire arc is as follows: Figure 7 As shown, it is 2.0 gf to 2.4 gf, and it can be seen that although it is a low arc, it has sufficient strength.

[0099] Figure 8 FIG. 2 is an image showing an example of a first bonding portion 54 formed by the technology disclosed in this specification. Figure 8 As shown, in the first joint 54 of this example, a portion of the wire 50 is placed on the flat disc-shaped crimping ball 60 at a predetermined interval and is compressed against the crimping ball 60. In addition, it can be seen that the wire 50 extends approximately horizontally from the forward end of the crimping ball 60, and the arc height HL can be suppressed to the wire diameter. About 1.1 to 1.2 times of.

[0100] Next, the process of automatically generating the movement sequence of the porcelain nozzle 12 by the control unit 24 is described. As mentioned above, the control unit 24 automatically generates the movement sequence of the porcelain nozzle 12. In order to automatically generate the movement sequence, the operator at least inputs the size information of the porcelain nozzle 12, the wire information, and the size information of the crimping ball 60 in advance. Here, the size information of the porcelain nozzle 12 includes the size values ​​of each part of the front end of the porcelain nozzle 12, that is, the hole diameter H, the chamfer diameter CD, the outer diameter T, the orientation width W, etc. In addition, the operator can also only input the identification information (such as the model) of the porcelain nozzle 12 instead of the size values ​​of each part. In the above case, the control unit 24 stores the size values ​​of multiple porcelain nozzles 12 in correspondence with the identification information in advance, and determines the size value of the porcelain nozzle 12 actually used based on the identification information input by the operator.

[0101] The wire information includes the wire diameter and material of the wire used. In addition, the size information of the crimping ball 60 includes the target values ​​of the diameter D and thickness Bt of the crimping ball 60 to be formed. Furthermore, the target values ​​of the diameter D and thickness Bt of the crimping ball 60 can also be automatically calculated by the control unit 24 based on other information. For example, the control unit 24 can also store the diameter D and thickness Bt of the crimping ball 60 that can be formed according to the shape of each porcelain nozzle 12 used and the wire diameter, and automatically determine the diameter D and thickness Bt of the crimping ball 60 based on the size information of the porcelain nozzle 12 and the wire information input by the operator.

[0102] In addition, the control unit 24 also obtains the position information of the first joint point P1 and the second joint point P2, that is, the position information of the pad 112 of the semiconductor chip 110 and the lead of the lead frame 120, before the sequence is generated. Such position information may be input by an operator or may be automatically obtained by the control unit 24. That is, for example, a camera that moves together with the bonding arm 14 may be pre-set near the bonding arm 14, and the control unit 24 calculates the positions of the first joint point P1 and the second joint point P2 based on the image captured by the camera.

[0103] If such information can be obtained, the control unit 24 calculates the moving position of the porcelain nozzle 12 in each moving track. Here, the calculation of the moving position of the tracks b to k for forming the first joint 54 will be described in particular. In order to calculate the moving position of the porcelain nozzle 12, the control unit 24 calculates the heights H1 to H3, the horizontal moving amounts Lb, the horizontal moving amounts L1 to L3, and the like.

[0104] Specifically, the control unit 24 calculates the crimping height H1, which is the distance from the upper surface of the gasket 112 to the lower end of the porcelain nozzle 12, in the first step (when the crimping ball 60 and the cylindrical portion 62 are formed) based on the thickness Bt of the crimping ball 60. In addition, the control unit 24 determines the moving height H2, which is the height when the porcelain nozzle 12 is horizontally moved in the third step, based on the type of the wire 50 (wire diameter, material, etc.). Furthermore, the control unit 24 determines the flattening height H3, which is the height when the wire 50 is flattened by the porcelain nozzle 12 in the third step, based on the crimping height H1 and the type of the wire 50 (wire diameter, material). That is, the flattening height H3 is a value obtained by adding a margin ΔH determined by the type of the wire 50, etc., to the crimping height H1.

[0105] Furthermore, the control unit 24 determines the horizontal moving distance Lb in the second step based on the maximum diameter (i.e., chamfer diameter CD) of the cylindrical portion 62. In addition, the control unit 24 calculates the number of times N of the squeezing action in the third step and the horizontal intervals L1 to LN of the squeezing action based on the shape of the porcelain nozzle 12 and the shape of the crimping ball 60. These values ​​N, L1 to LN are set in such a way that the wire 50 placed on the crimping ball 60 can be squeezing all of them using the facing surface 44 of the porcelain nozzle 12.

[0106] If the heights H1 to H3, the horizontal movement amounts Lb, and the horizontal movement amounts L1 to LN of each trajectory can be calculated, the control unit 24 combines these values ​​with the position information of the first and second joining points P1 and P2 to generate the movement sequence of the nozzle 12.

[0107] As shown in the above description, according to the wire bonding device 10 disclosed in this specification, a wire arc with a reduced arc height HL can be formed. In addition, according to the wire bonding device 10 disclosed in this specification, the movement sequence of the porcelain nozzle 12 that can achieve such a low arc can be automatically generated based on the shape information of the porcelain nozzle 12, the wire information, and the shape information of the crimping ball 60. As a result, the operator's work hours can be reduced.

[0108] Furthermore, the structure described so far is an example, and other structures may be appropriately changed as long as there is a control unit 24 that performs at least the following processing: a first processing (first step) to form the crimping ball 60 and the cylindrical portion 62, a second processing (second step) to move the porcelain nozzle 12 horizontally in order to cut the cylindrical portion 62, and a third processing (third step) to perform one or more flattening actions in the middle of moving the porcelain nozzle 12 in the forward direction.

Claims

1. A wire bonding device, which connects a first bonding point and a second bonding point provided on a mounted body by a wire, characterized in that: include: A porcelain nozzle for holding the wire; A moving mechanism, which enables the porcelain nozzle to move relative to the mounted body; and a control unit that controls the driving of the moving mechanism, and The control unit at least performs: The first process comprises: after a free air ball is formed at the front end of the wire, the porcelain nozzle is lowered to the first joint point to a specified crimping height, thereby forming a crimping ball and a cylindrical portion located on the crimping ball at the first joint point; A second process, after performing the first process, moving the porcelain nozzle horizontally at the crimping height, thereby cutting off the cylindrical portion with the porcelain nozzle; as well as The third process is to move the porcelain nozzle in a forward direction which is a direction approaching the second joining point at a moving height higher than the crimping height after executing the second process, and to repeat the flattening action more than once in the middle of the movement, wherein the flattening action temporarily lowers the porcelain nozzle in order to flatten the wire portion overlapping on the crimping ball with the porcelain nozzle.

2. The wire bonding device according to claim 1, wherein: In the second process, the control unit causes the porcelain nozzle to horizontally move in a retreat direction that is a direction away from the second joining point.

3. The wire bonding device according to claim 1 or 2, characterized in that: In the second process, the control unit causes the porcelain nozzle to horizontally move at least an amount equal to or greater than the diameter of the cylindrical portion.

4. The wire bonding device according to claim 1 or 2, wherein: In the third process, the control unit changes the horizontal position of the porcelain nozzle and performs the squeezing operation twice or more in order to completely press the wire portion overlapping the crimping ball with the porcelain nozzle.

5. The wire bonding device according to claim 1 or 2, wherein: The control unit generates a moving order of the porcelain nozzle based on the shape information of the porcelain nozzle, the target shape information of the crimping ball, and the information of the wire.

6. A method for manufacturing a semiconductor device, wherein a first junction point and a second junction point are connected by a wire using a porcelain nozzle to manufacture a semiconductor device, characterized in that: include: The first step is to form a free air ball at the front end of the wire inserted into the porcelain nozzle, and then lower the porcelain nozzle to the first joint point to a specified crimping height, thereby forming a crimping ball and a cylindrical portion located on the crimping ball at the first joint point; The second step is to move the porcelain nozzle horizontally at the crimping height after executing the first step, thereby cutting off the cylindrical portion with the porcelain nozzle; as well as The third step is to move the porcelain nozzle in a forward direction which is a direction approaching the second joining point at a moving height higher than the crimping height after executing the second step, and to repeat the flattening action more than once in the middle of the movement, wherein the flattening action is to raise and lower the porcelain nozzle in order to flatten the wire portion overlapping on the crimping ball with the porcelain nozzle.

7. A semiconductor device, wherein a first bonding point on a semiconductor chip and a second bonding point on a lead frame on which the semiconductor chip is mounted are connected via a wire arc, characterized in that: The line arc has: A first joint portion formed at a first joint point; and a second bonding portion formed at the second bonding point and connected to the first bonding portion via a wire, The first joint portion is shaped such that a portion of the wire is placed on a flat disk-shaped press-bonding ball at a predetermined interval and is compressed against the press-bonding ball. The wire extends substantially horizontally from an end of the first joint portion.

8. The semiconductor device according to claim 7, wherein: The arc height, which is the distance from the upper surface of the semiconductor chip to the highest point of the wire arc, is smaller than the total value of the thickness of the press-bonded ball and the diameter of the wire, or is equal to the total value.

Images